1. Technical Field
The invention relates generally to the field of electro-convulsive therapy. Specifically, the invention relates to a system and method of administering focused electro-convulsive therapy using titration in the current domain.
2. Description of the Related Art
Seizure therapy was first recognized as a viable treatment for Schizophrenia in 1934 by the Hungarian neuropsychiatrist Von Meduna. Early seizure therapies used pharmacological inducement methods. These early pharmacological methods were plagued by adverse side effects and unpredictability. In 1937, two Italian physicians, Cerletti and Bini, used electrical stimulation to induce the seizures for the seizure therapy. The success of this method quickly led to its adoption throughout the world. The use of electrical stimulation to induce seizures is generally referred to as electro-convulsive therapy (ECT).
ECT was in widespread use in the 1940's and 1950's for treatment of many severe mental health disorders including schizophrenia. However, the development of pharmacological alternatives to seizure therapy in the mid-1950's signaled the decline of ECT use. Currently, ECT is only sparingly used. However, due to limitations in the pharmacological alternatives, many psychiatrists have recognized the continuing viability of ECT and some have suggested that ECT use may be increasing.
Early ECT systems used standard 50 or 60 Hz sine wave electrical signals as this type of signal was readily available on the consumer power grid. Once researchers had established a set of stimulus parameters that was effective at producing seizures, there was no longer a need for ECT systems to have parameter varying controls. Consequently, some early ECT systems were not much more than a wall outlet plug, a voltage or current knob, and an ON/OFF switch.
Eventually, the electrically induced signals were associated with adverse side effects in the patients such as confusion and amnesia. This led researchers to experiment with the stimulus signals to try to reduce or eliminate the side effects of the treatment. This research led to ECT devices capable of providing a pulse waveform stimulus. Further, prominent ECT researcher, Paul Blachley, decided that, an optimal ECT device should incorporate the capability of monitoring both electroencephalograph (EEG) and electrocardiogram (ECG) signals, have the ability to test the safety of the electrical circuit before delivering the stimulus, and have the ability to allow careful titration to individuals' seizure thresholds. After design and testing efforts, the device envisioned by Blachley, which was known as the MECTA (Monitored Electro-Convulsive Therapy Apparatus) went on the market in 1973, and readily grew in popularity over the following years. Additional improvements continued to be made to the MECTA system over the years including safety improvements and the capability of continuous signal monitoring during treatment.
Conventional ECT systems use alternating current (ac) signals. Typically, when using ac signals to generate seizures, symmetric electrodes are used on the patient. Since the electrodes are symmetric and the current is bidirectional, the current distribution in the patient will be essentially symmetric in the vicinity of both electrodes. Consequently, with conventional ECT systems, the ability to focus the electrical signals on a specific portion of the patient's brain is extremely limited.
Also, in administering ECT, it is important to calibrate the ECT system to the individual patient's seizure threshold. This process is called titration. The titration process is important to ensure that seizures are generated in the most efficient way possible. Efficiently generating the seizures allows for more effective treatment and minimizes the side effects of the treatment to the patient. Conventional ECT systems use a total charge energy titration method in which the pulse width or number of pulses of the signals is manipulated until the patient's seizure threshold is reached. Unfortunately, it is not possible in conventional systems to perform the titration process by varying only the current. However, the ability to perform a titration process by only adjusting the current, may lead to more efficient determination of the patient's seizure threshold and minimize adverse side effects to the patient.
The invention addresses these and other disadvantages of the conventional art.